Yujeong, who works as a night shift nurse at a general hospital's cardiology department, is now told that her 12th-grade younger sister, Kijeong,

讲述在三次旅行中一起度过12个夜晚的两个男女的旅行罗曼史，是韩国版“before系列”（before sunrise，before sunset，before midnight），该剧还将以旅行为媒介描写主人公们的成长故事。